Letters Latent (LL)
In a Letters Latent clue, every instance of one letter — to be deduced — must be removed from the answer when it is entered into the grid. To help, the wordplay leads to the mutilated form to be entered, although the definition refers to the unmutilated answer.
Thus, the clue Interrogates spymaster in America leads to the answer PUMPS (interrogates), with P latent, and grid entry UMS. The wordplay suggests M (spymaster in James Bond novels) in US (America).